Vibration sensor

Abstract

A single vibration sensor producing multistage outputs corresponding to various vibrational acceleration values is disclosed. This vibration sensor is the type in which vibrational acceleration causes a movable gravitation element to move, and the movement of the element exerts pressure on a plunger which actuates a switch mechanism and outputs a signal. A feature of this vibration sensor is the switch mechanism includes a number of discrete switch units each having a different operating sensitivity. The switch units have a number of movable members which are displaced by the plunger when the vibrational acceleration causes the movable gravitation element to move, and a number of fixed contacts corresponding to these movable members with which the movable contacts come in contact. The spatial relationship of the fixed contacts with respect to the movable members is a feature which determines the operational sensitivity.

What is claimed is: 
     
       1. A vibration sensor for sensing a vibrational acceleration, comprising: a movable gravitation element which is movable by a vibrational acceleration;   a plunger detecting a movement of said movable gravitation element; and   a switch mechanism actuated by said plunger, said switch mechanism comprising a plurality of switch units each having a different operating sensitivity.   
     
     
       2. The vibration sensor according to claim 1, wherein each of said plurality of switch units, comprises: a movable member actuated by said plunger which is displaced by said movable gravitation element; and   a plurality of fixed contacts to come into contact with said movable element, wherein the operating sensitivity of each of said plurality of switch units is adjusted by a spatial relationship of fixed contacts with said movable member.   
     
     
       3. The vibration sensor according to claim 1, wherein each of said plurality of switch units, comprises: a plurality of movable members actuated by said plunger which is displaced by said movable gravitation element; and   a plurality of corresponding fixed contacts to come into contact with said plurality of said movable elements, wherein the operating sensitivity of each of said plurality of switch units is adjusted by a spatial relationship of said fixed contacts with respect to said movable member.   
     
     
       4. The vibration sensor according to claim 1, 2, or, wherein said movable gravitation element is a sphere. 
     
     
       5. The vibration sensor according to claim 1, wherein said operating sensitivity of each of said plurality of switch units is adjusted by a means for adjusting said spatial relationship of said fixed contacts with said movable member. 
     
     
       6. The vibration sensor according to claim 5, wherein said adjusting means adjusts a gap between said fixed contacts and a movable contact on said movable member. 
     
     
       7. The vibration sensor according to claim 1, wherein said switch units are snap-action type switches. 
     
     
       8. The vibration sensor according to claim 1, wherein said movable gravitation element moves onto a plurality of inclined surfaces corresponding to said different operating sensitivities, when an incline component force F 2  ' of vibration acceleration force F 2  becomes larger than an incline component force F 1  ' of gravitation acceleration force F 1 . 
     
     
       9. The vibration sensor according to claim 1, 2, or 3, wherein said movable gravitation element is a pendulum.